1. Field of the Invention
The invention relates to an apparatus used for the imaging of low intensity soft x-ray and ultraviolet electromagnetic radiation and charged particles. More particularly, the invention relates to an apparatus used for the imaging of low intensity soft x-ray and ultraviolet electromagnetic radiation which has high spatial resolution, low noise and excellent linearity.
A need has existed in celestial research for a soft x-ray and ultraviolet radiation detector having high one or two dimensional spatial resolution which permits full utilization of focusing and dispersing optics found in telescopes. When combined with an image forming optical system such a detector permits efficient spectroscopic measurement of extended sources or sensitive detection of point images whose positions are unknown. High resolution imaging is particularly advantageous when a point object is to be detected in the presence of a diffuse background as in many x-ray applications.
2. Description of the Prior Art
The development of apparatus for imaging soft x-ray and ultraviolet images of extremely low intensity such as those produced during celestial observation of distant points in outer space has progressed from simple exploratory photometric techniques employing large area collimated gas proportional counters, channel electron multipliers and photomultipliers to grazing incidence telescopes in soft x-ray astronomy and concave grating spectrometers in the study of planetary atmospheres.
A publication authored by the inventors of the present invention entitled "The Ranicon: A Resistive Anode Image Converter" appearing in Review of Scientific Instruments, Vol. 45, No. 9, September 1974, contains a comprehensive discussion of apparatus related to the present invention.
Charged particle detectors which detect the position of particle impact and measure particle energy are described in a publication entitled "A Hybrid Approach to Two Dimensional Charged Particle Position Sensing Preserving Energy Resolution" by W. M. Augustyniak, W. L. Brown and H. P. Lee published in the IEEE Transactions on Nuclear Science, NS-19, No. 3, p. 196 (1972). These devices detect the energy of a charged particle by sensing the number of electrons emitted from the surface of a semiconductor target upon particle impact thereon. The position of particle impact is detected by a chevron configuration of cascaded microchannel electron multiplier plates which are coupled to a resistive collector plate.
A charged particle detector of the aforementioned type differs fundamentally from the present invention in that detection of charged particles is accomplished within the semiconductor target prior to amplification by the chevron configuration of cascaded microchannel electron multiplier plates. On the other hand, both detection and amplification of soft x-rays, ultraviolet electromagnetic radiation or charged particles by the present invention is accomplished within a chevron configuration of cascaded microchannel electron multiplier plates.